Air-powered cutting tool for hair and the like



July 26, 1966 G. M. MAGARIAN 3,262,199

AIR-POWERED CUTTING TOOL FOR HAIR AND THE LIKE Filed June 4, 1964 2 Sheets-Sheet 1 July 26, 1966 G. M. MAGARIAN 3,262,199

AIR-POWERED CUTTING TOOL FOR HAIR AND THE LIKE 2 Sheets-Sheet 2 Filed June 4, 1964 62E/:ALD M Maan/@RAG INVENTOR.

BY 31; gm

United States Patent vO 3,262,199 AIR-POWERED CUTTING TUGlL FOR HAIR AND THE LiKE Gerald lid. Magarian, Long Beach, Calif., assignor to Preco Incorporated, Los Angeles, Calif., a corporation of California Filed .lune 4, 1964, Ser. No. 372,649 14 Claims. (Cl. 3ft-133) This invent-ion has to do generally with improved structure for powered hair clippers and for cutting tools of similar type.

Electrically driven clippers having a cutting head with relatively oscillatable toothed blades have become widely accepted for clipping hair, both professionally and in the home, and also for such cutting operations as trimming cloth or threads in connection with sewing, upholstering and the like. A source of inconvenience in all such operations is the problem of disposal of the cuttings.

The patent literature contains many proposals for providing a suction orifice closely adjacent the cutting head of such devices, and for connecting that orice to the suction end of a vacuum cleaner. Such provision for disposal of the cuttings may be added to a conventional electrically driven clipper,y but only at the cost of increasing its bulk and its .already excessive weight. It has therefore been proposed to eliminate the electric motor by driving7 the cutter head by an air turbine powered by the same vacuum that disposes of the cuttings. However, the technical problems of obtaining sufiicient power in that way have proved so difficult that none of the proposed structures has received public acceptance.

A primary purpose of the present invention is to provide a vacuum powered cutting tool of the described type that is fully effective and practicable.

More particularly, this invention provides a cutting tool that is satisfactorily compact and appreciably lighter than an equivalent electrically driven tool; that is remarkably economical to produce; that is quiet in operation and free from undesirable vibration; and that has relatively few moving parts that require a minimum of servicing but are readily accessible for inspection or other servicing when needed.

The present invention further overcomes a difficulty that has been recognized by much of the prior art, namely, the danger that cuttings may collect inside the housing, eventually clogging the air passages or physically block- -ing rotation of the air turbine. Several previous devices avoid that difficulty by providing separate airstreams for disposing of the cuttings and for driving the turbine. That, however, seriously reduces the turbine power that is available, especially when the cutter is used with a vacuum cleaner of limited capacity.

The present invention utilizes the entire airstream both for disposing of the cuttings and for driving the turbine. Clogging of the turbine is avoided, however, by providing a single, undivided air conduit from the intake orifice to the outlet at the suction tube, by providing ample clearance between the turbine and housing for passage of the cuttings, and by providing free communication between the suction tube and a large peripheral portion of the turbine rotor on the side opposite to the air inlet nozzle. Any cuttings that have adhered to a turbine blade at the nozzle tend to be freed by centrifugal force as the blade passes the suction tube, and are then immediately removed from the turbine chamber. That action is aided by passage of spent air radially outward over the turbine blades in that same portion of their travel, so that debris deposited on a turbine blade by air flow in one direction tends to be removed by the immediately following air ow in the opposite direction.

3,262,199 Patented July 26V, 1966 Furthermore, the individual turbine blades are straight formations of approximately uniform but slightly tapering section, supported at only one end and free at the other end. That construction greatly facilitates removal of any debris that might become wound about a blade despite'the novel air action just described.

A further important aspect of the present invention provides a coupling mechanism between the turbine and cutting head that has greatly reduced loads on all bearings where high relative velocity can occur. Because of these reduced loads it is feasible to use plain bushings throughout the device, some entirely unlubricated, and still avoid excessive friction losses and abnormal wear rates. The turbine speed is held to a low value suitable for cutter operation by a simple centrifugal governor mechanism, which has the further advantage of greatly reducing the speed v-ariations that would otherwise result from such factors as varying cutting loads and varying vacuum capacity of the power source. Although this aspect of the invention typically leads to operating the turbine at a speed far below that at which it would deliver maximum power, the power developed at these speeds is entirely adequate. Furthermore, at these low speeds the turbine develops very nearly its maximum torque.

The reduction of friction results, particularly, from mechanism for applying cutting force between the blades of the cutting head with a minimum of friction load; and by taking the driving torque from the turbine shaft at a crank pin having a throw many times greater than the blade movement to be produced. For a given value of torque transmitted to the cutter, that large -crank throw involves reduced friction, due primarily to the lower forces normal to the bearing surfaces, not only of the initial stages of the linkage but also of the turbine shaft itself. Also, the large crank throw is coupled to the relatively small movement of the cutter head by linkage mechanism that is not required to support other forces. Hence it can be designed for maximum lightness and freedom of movement.

A full understanding of the invention, and of its further objects and advantages, will be had from the following description of a preferred manner of carrying it out, of which description the accompanying drawings form a part. The particulars of that description are intended for illustration only, and not as a limitation upon the scope of the invention, which is defined in the appended claims.

In the drawings:

FIG. 1 is a plan view of an illustrative embodiment of the invention, with the top cover removed;

FIG. 2 is a longitudinal vertical section on the line 2-2 of FIG. 1, at enlarged scale;

FIG. 3 is a bottom view corresponding to FIG. l, with the bottom cover removed;

FIG. 4 is a front end elevation;

i FIG. 5 is a section on line 5 5 of FIG. 2; and

FIG. 6 is a section on line 6 6 of FIG. 2.

The present illustrative clipper comprises a main base 20, on which all the working parts are mounted. Base 20 is of generally at form, extending the entire width of the tool and is typically a zinc die casting or the like. The tool housing is completed by top and bottom cover members 34 and 36, respectively, referring to the orientation of the instrument as shown in FIG. 2, which is assumed for clarity of description in the specification and claims without implying any limitation upon the actual orientation. The covers are typically molded of a hard, but slightly flexible plastic, and are removably mounted on base 20 by resiliently snapping over the detent arm formations 38. Arms 38 are integrally formed on the 4 base and engage internal ridges 39 of the covers, as shown best in FIG. 5. In the present design, the edge 37 of base is exposed along both sides of the tool between the two covers. The covers are independently removable by light prying action, lproviding remarkably easy and cornplete access to the operating mechanism for upkeep and repair.

The rearward end of base 20 carries the integrally formed ring 22 adapted for connection of a flexible hose 23 from the intake end of a vacuum cleaner or other source of vacuum. The extreme forward end portion of base 20 is inclined upwardly at 24 (FIG. 2), and its forward edge 2S forms the lower lip of an air intake orifice. The inclined portion 24 of the base carries two transversely spaced downwardly extending bosses 26 which form inclined faces 27 on which the fixed blade member 80 is mounted by the screws 81. An upwardly extending hollow boss 30 is integrally formed centrally of base 20, and is internally finned at 31 to receive the turbine bushing 32, in which the turbine shaft 51 is journaled by means of upper and lower axially spaced plain bearings on a vertical axis indicated at 56.

Turbine wheel 50 comprises the hub 52, in which the turbine shaft 51 s press-fitted, the generally conical skirt portion 53, and the rim portion 54, which lies in a radial plane and carries the axially extending turbine blades 55.

The blades are of essentially uniform section, cupped as shown best in FIG. l, and slightly tapered toward their upper ends, which are free.

Air is supplied to the turbine via the intake conduit indicated generally at 60. The lower portion of that conduit is formed by the inclined surface 24 of base 20 and by side walls 61 which are formed integrally with the base. The upper portion of the conduit is formed by the nozzle cover 62, typically a die casting formed independently of base 20. It is ixedly mounted as by the rivets 59, on fiat surfaces 58 formed on the base (FIGS. 1 and 5). The forward edge 66 of the nozzle cover roof 63 meets ltop cover 34 somewhat back of its forward edge (FIG. 2). The latter edge thus defines, with forward edge 25 of base 20, the actual intake orifice of air conduit 60. The mating side wall portions 64 of nozzle cover.

62 and 61 of base 20 define the conduit curvature, as shown best in FIG. l, directing air obliquely radially inward toward turbine blades 55 with a large circumferential component of velocity in a counter-clockwise direction. The nozzle cover terminates rearwardly in a vertical wall portion 68, the upper edge of which approximately ts the inner surface of top cover 34. That wall is cylindrically curved about turbine axis 56 and abuts a similarly curved wall 28 that extends upwardly from base 20, together forming the front wall of the turbine chamber. That wall is pierced by the large nozzle orifice 69 that forms the rear termination of conduit 60. That orifice extends axially for the full height of the turbine blades and extends angularly for approximately 90 about turbine axis 56 from approximately the longitudinal midplane of the tool at the forward side of the turbine to the region 67 (FIGS. 1 and 6) where the turbine is essentially tangent to the side wall of the housing. Air from the nozzle strikes blades 5S nearly tangentially with highly eliicient driving force. That tangential impact is attained by designing the side walls of passage 60 in such a way that the axis 65 of the passage curves first to the left, as shown in FIG. l, and then curves smoothly to the right, meeting the periphery of the turbine at an acute angle. It will be noted (FIG. 5) that the transverse width of passage 60 is greater in the plane of that curvature (essentially horizontal) than in the plane normal to the curvature (essentially vertical).

In accordance with one aspect of the present invention, the turbine chamber has no cylindrical wall closely adjacent the turbine blades at the rear of the turbine and corresponding to forward wall 28, 68. Instead, the turbine communicates freely at its rear side with the open interior of the housing, from which air is drawn directly via outlet orice 22 to suction hose 23. As a result of that structure, the turbine driving air, after passing radially inward between the turbine blades, flows freely around the hub structure of the turbine wheel. Part of the air then flows through the passage 70 between top cover 34 and the turbine blades at the rear of the turbine, while the remainder of the air passes radially outward between the turbine blades, as indicated at 72 (FIG. l). The latter air stream supplements the action of centrifugal force in clearing the blades of any foreign matter such as long threads or hairs that may be carried into inlet conduit 60 and not pass freely through the blade assembly. For example, if foreign matter becomes lodged on one or more blades as the airstream passes through them in either direction, it is effectively removed by the oppositely directed airstream after rotation of the turbine through 180. The ample clearance between the turbine blades and the side walls of top cover 34 at 67, and also 'between the blades and cylindrical front wall 28, 68, prevents such foreign matter from jamming the turbine, insuring that it will be carried along the wall surface to the rear side of the turbine. The complete absence of any confining wall around the rearward periphery of the turbine greatly -facilitates the movement of cuttings from the turbine to suction hose 23. That open construction at the rear of the turbine has the further advantage that a maximum portion of the available pressure drop between atmospheric pressure outside the housing and the reduced pressure at outlet orifice 22 is concentrated in the highly etlcient primary driving jet from conduit 60.

The turbine speed is limited approximately to a predetermined value by a speed control mechanism typically comprising the two governor arms 40, which are pivoted near one end on the lower face of rim portion 54 of the turbine `by means of pivot pins 42, preferably molded integrally with the turbine. Centrifugal force due to turbine rotation swings the arms 40 radially outward against the inner face of the circular flange 44, formed integrally on the upper side of base 20. The resulting friction increases essentially in proportion to the square of the turbine speed, setting an effective maximum speed under zero load conditions, and holding the speed within a reasonably small range during wide variations of load and also of available pressure differential. The speed control mechanism is designed to limit the turbine to a maximum speed that is only a fraction of the value at which it would develop maximum power.

Base flange 44, which acts as brake drum for the speed control mechanism, is preferably surrounded by a circular channel 45 in the upper face of base 20. A downwardly extending peripheral liange 46 is provided on the turbine wheel and is received with ample clearance in channel 4S, forming a labyrinth which limits the travel.

of dirt between the turbine chamber and the small chamber 47 between the turbine wheel and base 20. As a further precaution against collection of dirt in the latter chamber, it is connected via an air passage to a source of air at a pressure higher than that in the main turbine chamber. Such air is admitted to chamber 47 from the relatively large chamber 48 on the lower side of base 20. In the present structure one or more relatively large apertures are provided in the base itself, as indicated in FIG. 2 at 43, between chambers 47 and 48, and the amount of air supplied through such apertures is limited by restricting the flow into chamber 48 from the surrounding atmosphere. Structure for such air tlow restriction is shown at 130 and is described below in connection with the mechanical linkage between turbine and cutting blades.

Fixed cutter blade is mounted -by the screws 81 on the oblique mounting pads 27, which are formed on downwardly extending bosses on base 20, as already mentioned. Blade 80 extends transversely of the tool and is provided with a row of conventional cutting -teeth 83 along its upper edge. The movable cutting blade 34 is pressed llatly against the inner and upper face of fixed blade 80, and carries a row of cutting teeth 85 along its upper edge, which is parallel to that of blade 80. Oscillation of the movable blade parallel -to the length of the blades causes the two rows of teeth to cooperatein the usual way to shear any cuttable object entering the V- grooves between adjacent teeth. The relative 4position of the two blades, the resilient force pressing them together, and the oscillatory movement of one vblade relative to the other are all controlled through the actuator plate 90, the forward end of which typically carries two fingers 92 which engage a V-groove formation 94 on the movable blade. Fingers 92 are-spaced longitudinally of the blade, as shown best in FIG. l, and their outer edges tittingly engage the end faces of groove 94. The position of the movable blade in the plane of the blades is thus positively defined by fingers 92. However the movable blade is free to rotate about the axis of groove 94 to accommodate to the plane of fixed blade S0.

Actuator plate 90 extends Substantially the entire length of the tool housing. Its rear end is pivotally mounted at 96 on the under side of base 20. The forward end of plate 90 is yieldingly urged downward by the compressed coil spring 100, which extends between respective seat formations on the plate and on the Linderside of base 20. Spring 100 is designed to produce the desired loading force between the -two cutting blades, typically of the order 3 to 5 lbs. The midportion of plate 90 is offset downwardly at 97 to clear driving mechanism to be described. Side flanges 98 on offset portion 97 render it essentially rigid. The forward portion of the plate may be slightly flexible, at least in torsion about its longitudinal axis, to insure approximately uniform division of the load of spring 100 between the two bladeengaging fingers 92. However, plate 90 is preferably prevented from significant rotation about its longitudinal axis, as by the two bosses 99, which project downward from base 2t) on opposite sides of pivot 96 nearly to the upper face of the plate (FlGS. 3 and 6).

Oscillation of actuator plate 90 about pivot 96 is driven from turbine 50 by the coupling mechanism indica-ted generally at 110, which is designed in novel manner to minimize loads in the turbine and connecting rod bearings. Coupling mechanism 110 comprises a relatively short lever 111 pivoted on the pivot pin 112, which fixedly projects downward from base 20. The forward end of lever 111 forms a cylindrical cam formation 113 which drives the two spaced parallel cam followers 114, xedly mounted on actuator plate 90. The'follower faces are perpendicular to the plane of plate 90 and generally parallel to its longitudinal axis, `typically comprising tabs formed from the plate. A sleeve element 115, typically of a plastic material having low coefficient of friction, is preferably interposed between cylindrical cam 113 and parallel followers 114, acting as a bearing. Cam arm 111 is driven from a crank pin 120, eccentrically mounted on turbine shaft 51 by means of the crank wheel 121. The connecting rod 122 is pivoted at its rear end on crank pin 120 and its forward end is pivotally connected at 123 to the free end of the lever 124. Lever 124 is formed integrally with lever 111, or otherwise fixedly connected to it, those -twolevers typically forming a bell crank lever. Turbine rotation thus causes that bell crank to oscillate about pivot 112. The resulting oscillation of cam arm 111 drives actuator plate 90 in a relatively small angular oscillation about its pivot 96. The movement of the forward end of plate 90, which is essentially translational, is transmitted to blade 84 by fingers 92.

The radial length of lever 124 with respect to pivot 112 is appreciably longer than that of cam lever 111. The ratio of the effective lengths of those two levers is typically from about three to about ten, the range from four to eight being preferred. That ratio of the effective lever arms requires that the radius of crank pin 120 from turbine axis 56 be many times larger than would be required with a more conventional linkage having a mechanical advantage of approximately unity. Moreover,

the linkage is such that the relatively large crank amplitude is not applied directly to the relatively sturdy actuating plate, but only to the connecting rod 122 and driving levers 111 and 124. Those elements are not subject to any forces other than those required to transmit the drive, and can be relatively ligh-t. The main lbody of plate 90, which takes the relatively large force of loading spring 100, moves less than the cutting blade, not more.

The abnormally large throw of crank pin has the advantage that the force transmitted by connecting rod 122 is small compared to that applied to actuator plate at cam 113. Hence the connecting rod may be extremely light and its bearings may be of simple and economical type. The reaction forces exerted on the turbine shaft bearings are correspondingly reduced. In preferred form of the invention, connecting rod 122 and levers 111 and 124 are formed of a suitable plastic that is hard and dimensionally stable and has low coefficient of friction, such as nylon or the polyacetal known commercially by the trademark Delrin, for example.

A further advantage of the present coupling structure is that the spring force for loading the cutting blades is applied in a manner that involves essentially no friction, other than that resulting directly from the desired pressure between the two blades. In particular, spring 100 exerts a generally downward force on actuator plate 90 without frictionally resisting its transverse oscillation. Since the point of application of that spring force to plate 90 is close to the blade and relatively far from plate pivot 96, the effective spring force at that pivot is correspondingly small. The friction at pivot 96 is therefore essentially negligible, especially in view of the very slight angular movement of plate 90, which typically amounts to only approximately 1.2 degrees in the present design. Even that friction may be eliminated, if desired, by replacing pivot pin 96 by a spring hinge, typically comprising a small section of spring sheet in a vertical plane connecting the rear end of plate 90 to base 20. Such a spring hinge may be quite light in view of the small forces that are involved, as already explained.

With the described type of coupling mechanism it has been found feasible to drive the cutting blades directly from the turbine shaft without gear reduction and with the turbine speed limited to a value of the order of 3000 r.p.m. Whereas that value is far below the maximum power speed of an air turbine, which is typically of the order of 10,000 r.p.rn., it is close to the speed at 4which maximum torque is available. With the efficient turbine design and the low friction losses provided by the described coupling mechanism and blade drive, operation is highly satisfactory even when only moderate vacuum is available.

Lower cover 36 ts the periphery of base 20 closely except at the forward end, where a relatively large opening is provided at 49 between the front edge of the cover and the blade structure. The reduced pressure of the air stream entering main inlet 60 draws air from 49 upwardly over the inner surface of the blades between and around bosses 26 and out into passage 60 between blade 34 and the forward edge 25 of the base. Air flow from 49 into main lower chamber 48 is limited, in the structure shown, by la barrier comprising the wall 126 projecting downward from base 20 and the wall 128 projecting upwardly from the inner face of cover 36. The opposing edges of those walls are closely spaced from actuator plate 90, forming a horizontal slot 130 that is just long enough to clear the oscillatory movement of the plate. Slot 130 thus forms an orifice which admits air from opening 49 to chamber 48 in limited amount, suicient to provide steady flow of clean air radially outward between the skirt of the turbine and the base, but insufficient to significantly reduce the main fair jet that drives the turbine. That manner of controlling air ow through the labyrinth formed by flange 44 between turbine and base has the advantage that there is no axial variation of pressure along the main turbine bearings such as might produce air flow that would deposit grit in the bearings. The air pressure at opposite ends of the main bearing is equalized by providing passage structure between each of those ends and a common source of pressure, which is typically a portion of the passage system for flow between turbine and base. That pressure source is necessarily on one side or the other of the described flow-limiting orifice 130. That shunting passage structure may be considered to include the slight clearance at the thrust bearings 134 and 135, shown in exaggerated form at upper thrust bearing 134; or the thrust bearings may be considered to constitute the extreme end portions of the main bearing. In the present embodiment two passageways in parallel connect the two thrust bearings. One passageway includes the generally annular passage 138 between the fins 31 `which support bushing 32 within base boss 30, and the passage 136 between the periphery of crank hub 121 and bushing 32. The pressure in that passageway is essentially that of chamber 48. The other shunting passageway includes the limited orifice 132, annular chamber 47, Iand the large apertures 43 between chambers 47 and 48. Both those passageways communicate with chamber 48, which thus acts as a common source of pressure for supply to the opposite ends of the main bearing. With the main bearings thus shunted via the passage 138 between tins 31 and also via the large aperture 43, even an appreciable accumulation of cuttings or other debris within the housing cannot produce ya pressure drop across the main bearings. An alternative manner of limiting air flow through the described labyrinth omits the walls 126 and 128, so that chamber 4S is effectively open to the atmosphere at 49. Apertures 43 in base 20 are also omitted, so that the only commun-ication between chamber 48 and chamber 47 immediately below the turbine is via the generally annular passage between the tins 31. The air flow through that passage is essentially free except at the upper end, where the flow-limiting orifice 132 is formed between the turbine hub and the upper edge of boss 30. From orifice 132 the ow is then downward and outward through chamber 47 to the labyrinth at flange 44. With that alternative structure the two ends of the main bearing are shunted via passage 138 between fins 31 and passage 136. Despite the flow through the former passage, the pressure drop is negligible, since passage 138 olfers essentially zero resistance to flow compared to the flow-limiting orice at 132. In that modification the air flow is limited at orice 132 inwardly of the turbine bearings, whereas in the previously described embodiment the barrier 126, 128 of FIG. 2 limits the air ow at orice 130, outwardly of the turbine bearings. In either case, both axial ends of the turbine bearing are exposed to the same air pressure, protecting the bearing from dirt or other damage. When orice 130 is provided, orifice 132 may be made larger than shown, if desired, or those two orifices may be so dimensioned that the ow limiting action is divided between them.

I claim: 1. A vacuum driven cutting tool for hair and the like, comprising in combination elongated housing structure adapted to be hand held, a cutting head mounted at one end of the housing structure and comprising relatively movable toothed cutting blades, said housing structure enclosing a turbine chamber having generally at top and bot-tom walls and a generally cylindrical front wall, an air turbine journaled in the turbine chamber on an axis perpendicular to the chamber bottom wall and comprising a turbine wheel having an annular trim portion adjacent the bottom wall and circumferentially spaced turbine blades mounted on the rim portion and extending axially therefrom toward the top wall, the forward portion of Ithe turbine periphery being closely adjacent the front wall of the turbine chamber, and the rear portion of the turbine periphery and the axial face of the turbine opposite the rim portion being spaced from the housing structure and dening therewith an open portion of the turbine chamber,

structure forming an air intake adjacent the teeth of the cutting head,

passage structure for directing an airstream from the air intake obliquely toward the turbine through said cylindrical front wall in a tangential and radially inward direction,

air outlet structure adapted for connecting to a suction conduit and communicating with said open portion of the turbine chamber,

and coupling means for driving the relative movement of the cutting blades in response to turbine rotation.

2. A vacuum driven cutting tool for hair and the like,

comprising in combination an elongated housing adapted to be hand held,

a cutting head mounted at one end of the housing and comprising relatively movable toothed cutting blades,

structure forming a wall within the housing between a turbine chamber and a mechanism chamber,

a turbine shaft extending through the wall and journaled thereon,

an air turbine mounted on the shaft in the turbine chamber adjacent the wall,

coupling means connected to the shaft in the mechanism chamber for driving the relative movement of the cutting blades in response to Iturbine rotation,

structure forming an air intake adjacent the teeth of the cutting head for directing a driving airstream toward the turbine,

air outlet structure adapted for connection to a suction conduit and communicating with the turbine chamber,

and passage structure forming a path for airow from the atmosphere through the mechanism chamber and through said wall and radially outward between the wall-and the turbine into the turbine path, said passage including a restriction for limiting the airow,

said passage structure also forming passage means communicating between both axial ends of the shaft journal and said path on the same side of the restriction to equalize pressure across the journal.

3. A vacuum driven cutting tool as defined in claim 2, and wherein said turbine includes a hub portion and said passage restriction is formed by closely adjacent opposing surfaces of said wall structure and said hub portion.

4. A vacuum driven cutting tool as dened in claim 2,

and wherein said passage restriction is formed between the mechanism chamber and the surrounding atmosphere.

5. A vacuum driven cutting tool for hair and the like,

comprising in combination an elongated housing adapted to be hand held,

xed and movable blades mounted adjacent one end of the housing and having interengaging parallel toothed edges, the movable blade being slidable relative to Ithe fixed blade parallel to said edges in an oscillatory movement of predetermined blade amplitude,

a main lever mounted in the housing with one end engaging the movable blade and the other end pivotally mounted adjacent the other end of the housing, the lever being oscillatable about its pivot in a plane parallel to said blade movement to drive the same,

an air turbine carried by a turbine shaft journaled in the midportion of the housing and having an air inlet and an air outlet,

air intake structure adjacent the toothed blade edges and communicating with the turbine inlet,

air outlet structure adapted for connection to a suction conduit and communicating with the turbine outlet,

a crank pin mounted eccentrically on the turbine shaft with a crank throw between about three and about ten times said blade amplitude, and linkage means coupled to the crank pin and engaging the lever adjacent its said one end, said linkage means having a mechanical amplification less than unity and acting to drive the blade oscillation at said amplitude in response to turbine rotation. 6. A vacuum driven cutting tool as defined in claim and including also centrifugally actuated means for limiting the speed of the turbine to a value between about 1/5 and about 1/2 the speed at which the turbine would deliver maximum power. 7. A vacuum driven cutting tool as defined in claim 6 and wherein said linkage means comprise a bell crank lever pivotally mounted on a pivot axis perpendicular to the length of the main lever and having a long arm extending transversely of the length Vof the main lever and a short arm extending generally parallel to the length of the main lever and operatively engaging the same, the long arm being between about three and about ten times the length of the short arm, and a link pivotally interconnecting the crank pin and the free end of the long arm. 8. A vacuum driven cutting tool as defined in claim 6 and including also a coil spring acting between the housing and the main lever adjacent said one end thereof with the spring axis transverse of .the plane of movement of the main lever, said spring being tensioned to press the movable blade yieldingly against the fixed blade. 9.V A vacuum driven cutting tool for cutting hair and the like, comprising in combination an elongated, generally fiat base, a cutter head mounted on the base at the forward end thereof and comprising fixed and movable blades with interengaging toothed edges extending parallel to the v plane of the base on one Side thereof,

a turbine shaft journaled on the base intermediate its length on a turbine axis transverse of the plane of the base,

an air turbine mounted on the shaft on said one side of the base and comprising an annular rim coaxially mounted on the shaft closely spaced from the base and carrying axially extending circumferentially spaced turbine blades,

a first cover member releasably mounted on the base on said one side thereof and forming therewith a first housing chamber having an air inlet adjacent said blade edges,

air outlet structure mounted on the base at the rearward end thereof and adapted for connection of a suction conduit to draw air out of said first chamber,

structure carried by the base between the turbine and the cutter head for directing air from the air inlet obliquely against the turbine blades in a circumferential and radially inward direction essentially in a plane parallel to the base,

a second cover member releasably mounted on the base on the other side thereof and forming with the base a second housing chamber,

and coupling mechanism mounted on the base within the second chamber for driving the movable blade of the cutting head in response to turbine rotation.

10. A vacuum driven cutting tool as defined in claim 9 and wherein said base has two generally parallel side edges extending from the cutting head rearwardly to the air outlet structure, said side edges being approximately tangent to the periphery of the turbine, v

and said air directing structure forms a conduit adapted to receive a rearwardly owing airstream of elongated rectangular section bounded on one side by the toothed edges of the cutting head, said conduit having a longitudinal axis that curves in a plane generally parallel to the base first toward one side edge of the base and then toward the opposite side edge of the base, and said conduit having an outlet opening that extends continuously circumferentially of the turbine approximately from the middle of the forward side of the turbine to said opposite side of the base.

11. A Vacuum driven cu-tting tool as defined in claim 9 and wherein said coupling mechanism comprises a main lever pivotally mounted on the base adjacent the rearward end thereof for pivotal movement in a plane parallel to .the base, said lever extending forwardly between the base and the second said cover member, the forward end of said lever drivingly engaging the movable blade of the cutting head,

spring means acting between the base and said lever adjacent the forward end thereof to resiliently urge the movable blade into operative contact with the fixed blade,

a bell crank lever pivotally mounted on the base and having a short arm that extends generally parallel to the length of the main lever and drivingly engages the same near its forward end and having a long arm that extends parallel to the plane of the base and transversely of its length, a crank pin eccentrically mounted on the turbine shaft on said other side of the bas'e, and a link pivotally interconnecting the crank pin and the free end of the long arm, said long arm being between about three and about ten times the length of the short arm, and the throw of the crank pin being between about three and about ten times the total amplitude of movement of the movable blade.

12. A vacuum driven cutting tool ltl and wherein said base has a circular flange on its said one side coaxial of 4the turbine shaft and adjacent the periphery of the turbine rim,

there being a plurality of centrifugal elements pivotally mounted on the face of the turbine rim opposing the base, said elements swinging radially outward in response to centrifugal force into frictional contact with the inner face of said ange to limit the turbine speed to a value less than the speed at which the turbine would normally deliver maximum power.

13. A vacuum driven cutting tool for hair and the like,

comprising in combination an elongated housing adapted to be hand held,

a cutting head mounted at one end of the housing and comprising relatively movable toothed cutting blades,

structure forming a wall within the housing between a turbine chamber and a mechanism chamber,

a turbine shaft extending through the wall and journaled thereon,

an air turbine mounted on the shaft in the turbine chamber adjacent the wall,

coupling means connected to the shaft in the mechanism chamber for driving the relative movement of the cutting blades in response to turbine rotation,

structure forming an air intake adjacent the teeth of the cutting head for directing a driving airstream toward the turbine,

air outlet structure adapted for connection to a suction conduit and communicating with the turbine chamber,

and passage structure forming a path for airow from the atmosphere through the mechanism chamber and through said wall and radially outward between the wall and the turbine into the turbine chamber, said path including a restriction for limiting the airflow.

14. A vacuum driven cutting tool for hair and the like,

comprising in combination an elongated housing adapted -to be hand held and enclosing a turbine chamber,

as defined in claim a cutting head mounted at one end of the housing and comprising mutually parallel and relatively movable blades mounted generally transverse of the housing and essentially forming an end wall thereof, with interengaging cutting teeth along respective blade edges -that are parallel and adjacent,

an air turbine mounted in the turbine chamber and operatively coupled to the blades to drive their said movement,

air outlet structure adapted for connection to a suction' conduit and communicating with the turbine chamber to drive the turbine by suction induced air flow, structure forming a generally longitudinal air intake passage having a mouth adjacent the teeth of the cutting head and communicating with said air outlet structure to draw in cuttings from the blade teeth, and structure forming a passage for air ow generally References Cited by the Examiner UNITED STATES PATENTS 3,138,870 6/1964 Stachon 30-133 X FOREIGN PATENTS 611,073 10/1948 Great Britain.

WILLIAM FELDMAN, Primary Examiner.

R. V. PARKER, JIL, Assistant Examiner. 

1. A VACUUM DRIVEN CUTTING TOOL FOR HAIR AND THE LIKE, COMPRISING IN COMBINATION ELONGATED HOUSING STRUCTURE ADAPTED TO BE HAND HELD, A CUTTING HEAD MOUNTED AT ONE END OF THE HOUSING STRUCTURE AND COMPRISING RELATIVELY MOVABLE TOOTHED CUTTING BLADES, SAID HOUSING STRUCTURE ENCLOSING A TURBINE CHAMBER HAVING GENERALLY FLAT TOP AND BOTTOM WALLS AND A GENERALLY CYLINDRICAL FRONT WALL, AN AIR TURBINE JOURNALED IN THE TURBINE CHAMBER ON AN AXIS PERPENDICULAR TO THE CHAMBER BOTTOM WALL AND COMPRISING A TURBINE WHEEL HAVING AN ANNULAR RIM PORTION ADJACENT THE BOTTOM WALL AND CIRCUMFERENTIALLY SPACED TURBINE BLADES MOUNTED ON THE RIM PORTION AND EXTENDING AXIALLY THEREFROM TOWARD THE TOP WALL, THE FORWARD PORTION OF THE TURBINE PERIPHERY BEING CLOSELY ADJACENT THE FRONT WALL OF THE TURBINE CHAMBER, AND THE REAR PORTION OF THE TURBINE PERIPHERY AND THE AXIAL FACE OF THE TURBINE OPPOSITE THE RIM PORTION BEING SPACED FROM THE HOUSING STRUCTURE AND DEFINING THEREWITH AN OPEN PORTION OF THE TURBINE CHAMBER, STRUCTURE FORMING AN AIR INTAKE ADJACENT THE TEETH OF THE CUTTING HEAD, PASSAGE STRUCTURE FOR DIRECTING AN AIRSTREAM FROM THE AIR INTAKE OBLIQUELY TOWARD THE TURBINE THROUGH SAID CYLINDRICAL FRONT WALL IN A TANGENTIAL AND RADIALLY INWARD DIRECTION, AIR OUTLET STRUCTURE ADAPTED FOR CONNECTING TO A SUCTION CONDUIT AND COMMUNICATING WITH SAID OPEN PORITON OF THE TURBINE CHAMBER, AND COUPLING MEANS FOR DRIVING THE RELATIVE MOVEMENT OF THE CUTTING BLADES IN RESPONSE TO TURBINE ROTATION. 